Focal segmental glomerular sclerosis (FSGS) is not a single disease, but a pattern of kidney damage. It is one of the most common causes of nephrotic syndrome, especially in children and adolescents. Nephrotic syndrome occurs when the body loses large amounts of protein into the urine, often resulting in swelling of the body; over time, progressive scarring of the kidneys can lead to kidney failure.
Focal segmental glomerular sclerosis can be explained as follows:
- Is identified by the scarring, or “sclerosis,” of the kidney
- Damaged glomeruli
The kidneys’ filtering system is made up of glomeruli that work something like a kitchen colander. The body pours blood into the kidneys, and as it circulates, the water-like part of the blood escapes and becomes urine. In FSGS, these damaged glomeruli are scarred, and when water is filtered out of the blood, protein leaks out into the urine as well. This whole process is referred to as glomerulosclerosis.
- “Focal” — Not every filter is damaged
- "Segmental” — Only parts of each filter may be scarred
What Causes FSGS?
FSGS can be a result of an autoimmune disease, in which the body attacks itself without cause, or the result of a pre-existing medical condition such as the following:
- Kidney defects from birth
- Urine back-ups in the kidney
- Obstructive sleep apnea
- Sickle cell anemia
- Viruses (such as HIV)
FSGS is sometimes linked to a hereditary gene. Having a family member with FSGS may increase the chance of acquiring the disease. Most people do not know they have a genetic risk until symptoms begin. Some of the genes known to be associated with FSGS are alpha-actinin, WT1 and podocin. It is proportionally more common in African-Americans than other groups.
What Are the Symptoms of FSGS?
- Edema–Noticeable swelling in parts of the body, often visible around the eyes, hands, and feet
- Hypoalbuminemia–Low level of water-soluble protein [albumin] in the blood
- Proteinuria–Large amounts of protein in the urine
- Hypertension–High blood pressure
How Is FSGS Diagnosed?
A urine test is taken, and if protein is found, a kidney biopsy is done to see if there is kidney scarring. A biopsy revealing no scarring may lead to a different diagnosis called minimal-change disease, a kidney disease that is often effectively treated with steroids. It is important to return to the kidney specialist regularly to make sure the condition does not worsen.
How Is FSGS Treated?
FSGS is a severe form of nephrotic syndrome, and while no cure currently exists, medical care can improve the patient’s quality of life. It is important to try to reduce the amount of protein escaping from the kidneys, and ways to do that include a low sodium diet and avoiding non-steroidal anti-inflammatory drugs to help protect the kidneys.
Immunosuppressants & Steroids
These may be prescribed. However, FSGS is associated with a steroid-resistant gene, so most children with FSGS do not respond to any immunosuppressant therapy.
ACE-inhibitors (angiotensin converting enzyme inhibitors) and ARBs (angiotensin receptor blockers). Possible dialysis within a few years of diagnosis
If the patient’s condition continues to worsen, kidney failure may occur, and a kidney transplant would be needed. Receiving a kidney from a relative is ideal; because of the similarities between the donated kidney and the patient, the kidney may last longer. Learn more about kidney transplantation.
In some patients with FSGS, the condition can recur after kidney transplantation, sometimes as quickly as a few days. Because of this, kidney transplantation from a live donor may not be recommended in this situation.
This technique may allow for the removal of the FSGS factor and result in the slow disappearance of proteinuria after transplantation.
Provided the transplant functions well, dialysis will no longer be required. In some patients, however, the kidney transplant may not function forever. Receiving a second kidney transplant may be an option. Transplant success rates are approximately 95% after one year, 80% after five years and 70% after ten years.
Roughly 26 million Americans suffer from chronic kidney disease, FSGS being one of the most common forms, according to NephCure, a foundation of doctors and researchers committed FSGS research. Approximately 5,400 patients are diagnosed with FSGS every year.
About 14.4% of dialysis patients are being treated for FSGS, with children as the most prevalent group. Approximately 15% of FSGS patients have a kidney transplant, but because of recurrent FSGS, may lose the kidney.
Research involving Ann & Robert H. Lurie Children’s Hospital of Chicago, Northwestern University and collaborators around the country is continuing with the goal of prevention and effective treatment of FSGS.